Okay – who’s making us fat?

I don’t mean that we should try to wriggle out of personal responsibility– we are what we eat, folks, and nobody’s making us take seconds.

But who’s making all of us, worldwide, fat? According to a number of reports, the globe is bulking up for an era of mass obesity. This goes counter to what I have always thought of as accepted wisdom. According to the experts, this was supposed to be an era of mass starvation.

Global famine makes perfect sense. As the Reverend Thomas Robert Malthus pointed out two centuries ago, fast-growing populations outstrip their food supply. Do the math: population grows geometrically (two become four, four become eight, etc.) while food production grows, well, field by field, adding a few more acres here, eking out a few more bushels there, hoping for good weather. Population grows fast, food grows slowly. The logical result, Rev. Malthus pointed out, is starvation.

I grew up on books like The Population Bomb that echoed the theme; I joined a group called Zero Population Growth that sent out seemingly unassailable data doing the same; and I (with many others) bought into the prediction that the skyrocketing number of humans on earth meant that we were going to run out of food. Soon.

It did not happen as soon as Malthus thought because of the opening of the vast grain-growing plains of the American West and the Russian steppes. But those were just temporary delays. In 1898 the physicist Sir William Crookes, then-head of Britain's leading scientific association, noted that there were no more open plains to put under the plow and made worldwide headlines by trumpeting the coming starvation of the civilized world, starting no later than the 1940s.

Then we made it even worse by making it better.  As the twentieth century marched on, we invented antibiotics, lowered infant death rates, and extended average lifespans. The result?  Our global population skyrocketed, the statistics far beyond what the doomsayers had projected.  Surely now, it was thought in the 1960s, Malthus would be proven right.

It was then, with the population bomb ticking ominously, that Paul Ehrlich and a new generation of eco-activists took up the cry: Mass famine was coming soon to a nation near you. This time it was predicted to start in India in the mid-1970s. Again, it did not happen.

Instead, everywhere you look, from Buffalo to Brussels to Beijing, it’s ballooning bellies. Instead of mass hunger, mass fat. Instead of famine, India is suffering an epidemic of diet-related diabetes. Obesity is on the rise in virtually every developed nation and many less-developed nations from Europe, Asia, and North America to South Africa and Latin America. The shocker for me was a recent academic study asserting that there are now more overweight people in the world than hungry ones.

So who’s to blame? All the usual suspects are being trotted out: fast food, trans fat, high sugar, low exercise, television, blood chemistry, computer potatoes (like couch potatoes only with a game controller in their hands), and the associated problem of a seemingly hardwired human instinct that favors sitting around eating salty, crunchy snacks and drinking beer over of doing hard physical labor.

All of these factors are certainly related to the "insidious, creeping pandemic of obesity . . . now engulfing the entire world," as one gung-ho expert put it. But they are not the root cause.

The real issue is this: Malthus was wrong. He was not wrong about population growth. He was wrong about food. Food production has not only kept up with population growth, it has outstripped it. On average, humans are consuming more calories per person per day now than they were a century ago, despite the fact that total population has quadrupled. Somehow we beat the odds.

Who is to blame for this tidal wave of food? How are we creating the seas of cheap grains that we process with cheap sugars to make our donuts, and fry in lakes of fat to make our chips? Who is making it possible to eat hamburgers by the bag and guzzle soda by the gallon when we're supposed to be starving?

The answer is: a couple of guys you never heard of.

Back around the time Warren Harding was president these two Germans -- a genius chemist and a budding tycoon -- figured out a little trick that humans have been dining out on ever since.

They discovered how to make bread out of air.

That’s a fanciful way of saying it, but that’s what they called back in 1910 when Fritz Haber perfected the dangerous, complex chemistry needed to grab nitrogen out of the air (air is 80 percent nitrogen). Then Carl Bosch, a young chemist just starting his career, figured out how to build factories to turn it into synthetic fertilizer, the kind you get in a bag down at the local garden store.

They flooded the world with fertilizer. The results were a couple of Nobel Prizes and the creation of the world's largest chemical company (the infamous IG Farben, which Bosch headed).

Today, Haber-Bosch factories the size of small cities, much refined and improved, are humming around the world, burning 1 percent of all the energy used by humans each year on earth, breathing in hundreds of thousand of tons of air and pumping out hundreds of thousands of tons of fertilizer. This is the substance that enriches the fields that grow the crops that turn into the sugars and oils and meats that are cooked into the burritos and pizzas and snack cakes that make us fat.

If you doubt the importance of these two scientists, consider that if all these Haber-Bosch plants in the world were to shut down today, more than two billion people would starve to death. Or that half the nitrogen in your body is synthetic, the product of one of these factories.

The good news is that the Haber-Bosch discovery (along with the “Green Revolution” of higher-yield grain types developed in the late twentieth century) has allowed humanity to sidestep the Malthusian trap.

The bad news is that starvation has not gone away. People still starve to death, tragically, in isolated pockets of the world. The problem is not a lack of food to feed them; the problem is that the food cannot be moved quickly enough to where it is needed. Starvation today results almost always from distribution slowdowns due to local wars or government interference.

But the best news is this: If everything goes right, humans need never suffer global famine. Rising food prices, the subject of much recent media attention, are also tied to Haber-Bosch: The process burns a lot of natural gas, so when energy prices go up, so does the price of fertilizer -- and food.

Some time in the next few decades birth rates worldwide will dip below replacement levels. What that means is that the growth in world population will begin to slow, then eventually grind to a halt, some time after all the Babyboomers and most of their kids, the Baby Boomlet, die out. The human tide, in other words, will crest, then slowly ebb. The United Nations estimates that it will peak somewhere between 9 and 10 billion some time just after the middle of this century.

There will be a lot more mouths to feed. But if we eat wisely -- less meat and more vegetables, enough to be healthy but not enough to be obese – there will be enough food to feed everyone. Thanks to Haber-Bosch (and the Green Revolution), it is within our grasp to avoid mass starvation forever.

TOM HAGER (www.thomashager.net) is the author of the forthcoming The Alchemy of Air: A Jewish Genius, a Doomed Tycoon and the Discovery that Changed the Course of History.  His other books include The Demon Under the Microscope and Force of Nature.